1990 Pontiac Sunbird Runs Rough and Stalls?

[Cindy]

I have had a new exhaust put on the car after driving with a bad one for 6 months. All was well for the first day. Now the car when started will stall after 10-15 mins. The speedometer spikes and the check engine light comes on all while still in park. A diagnostic of the computer did not reflect any codes. The computer was replaced but the car performed worse, so the original computer was put back on. The mechanic has now installed a new Coolant Sensor. It appears to be working fine, but I am hesitant to go any distance with the car. Does anyone have any suggestions as to what may be causing the problems? The car has over 100,000 miles but has been reliable for the 4 years I have owned it. Bought it used for $1,000.00. I have not had to put much money into it above routine maintenance.

 

[farmer12]

Its possible the engine just needs a basic tune up, spark plugs, and wires, if any of that has never been changed with over 100k that would be a good place to start. It is possible that the coolent temp sensor was causing that, thats a tempermental little sensor that can cause lots of problems if its not working right.